The present invention relates to work guides for powered woodworking machines and, more particularly, to fences which are adjustably mountable on the tables of table saws.
A typical table saw includes a base which supports a subtantially flat tabletop having a transverse slot and a pair of side rails extending along opposite sides of the tabletop. A motor is mounted beneath the tabletop and a cutting tool, which may be a circular saw blade, is mounted on the output spindle of the motor and is positioned to project upwardly through the slot. The saw blade or other cutting tool rotates in a plane which is perpendicular to the central axes of the side rails.
In order to guide a workpiece in a feed direction which is at all times parallel to the plane of rotation of the cutting tool, work guides have been developed. A common work guide is a saw fence which comprises an elongate fence body which is adjustably mountable on the side rails and includes at least one flat guide surface which extends upwardly from the tabletop and is oriented parallel to the plane of rotation of the cutting tool. A lock-back is attached to one end of the fence body and adopted to engage a first one of the side rails. A base member is attached to the opposite end of the fence body and includes mechanisms for positively securing the lockback and base member to the side rails.
An example of such a saw fence is shown in Odlum et al. U.S. Pat. No. 2,740,437. That saw fence includes a lock-back consisting of a hook bolt which extends downwardly from the fence body and is tightened against the adjacent side rail (which, in this example is a downwardly-extending flange on the tabletop). The base member includes a transverse channel which receives a tubular side rail which extends outwardly from the tabletop, and is locked to the associated rail by a lever which, when pivoted downwardly, engages the rail with a bearing surface formed on its upper end.
A disadvantage with this type of saw fence is that it is somewhat awkward to attach the base member to or remove the base member from the tubular side rail. To attach the base member, it first must be positioned beyond the end of the rail, then displaced sidewardly so that the rail telescopes into the channel. Another disadvantage with this type device is that the base member may not always accurately square the base with the side rail so that the guide surface of the saw fence is parallel to the rotational plane of the cutting tool.
Another type of saw fence is shown in Gaskell U.S. Pat. No. 2,806,493. That patent discloses a saw fence having a base member which includes a transverse channel for receiving an adjacent side rail of the saw table. The base member includes a spring-loaded tensioner button which rides against the underside of the side rail and acts to hold the bracket downwardly against the fence. However, this type of saw fence lacks structure which positively locks the fence bracket against this associated side rail, and is secured to the tabletop by opposing clamping surfaces which engage the opposing edges of the tabletop. Furthermore, like the Odlum et al. device, this saw fence lacks structure for accurately squaring the saw fence relative to the cutting tool.
Accordingly, there is a need for a saw fence having a base member which permits the fence to be attached to or removed from the side rails of the saw table by a simple vertical displacement, rather than requiring the saw fence to be slid sidewardly off the ends of the side rails. There is also a need for a saw fence having a base member which is designed to perform a squaring action in addition to locking the saw fence against the side rails.